1. Field of the Invention
The present invention relates to a semiconductor device and a manufacturing method of the same.
2. Description of the Related Art
Semiconductor devices such as a CCD, CMOS image sensor using semiconductor integrated circuit technology are widely used for a digital camera and a cellular phone with camera function. In the semiconductor device as stated above, it is proposed that sensor chips (semiconductor elements) are made to be a CSP (Chip Size Package) to correspond to small in size and light in weight of mounted parts. It is studied that a penetrating wiring layer (a penetrating electrode) connecting between front and rear both surfaces is applied for a semiconductor substrate on which a sensor device and so on are formed when the semiconductor element such as the sensor chip is made to be the CSP.
The penetrating wiring layers are formed by providing through holes joining between front and rear both surfaces at the semiconductor substrate, and filling conductor layers inside this through holes. An integrated circuit including a light-receiving portion provided at the front surface of the semiconductor substrate and external connection terminals provided at the rear surface are electrically connected via the penetrating wiring layers. The integrated circuits, the penetrating wiring layers, and so on are formed during a wafer process. A case with optical lens is attached to the semiconductor device in which a semiconductor wafer is cut to be a separated piece (an image sensor and so on). This is mounted on a module substrate in a state as stated above, and thereby, a camera module is constituted.
A light-transmissive protective member is disposed on the semiconductor substrate so as to cover a region including the light-receiving portion, to protect the light-receiving portion provided at the front surface of the semiconductor substrate from dust and garbage (refer to International Publication No. WO 2005/022631 A1). The light-transmissive protective members such as glass substrates are disposed in parallel with predetermined intervals on the semiconductor substrate where the integrated circuits including the light-receiving portions are formed. The glass substrates are adhered to the semiconductor substrate by an adhesive resin disposed so as to surround an outer edge of the light-receiving portions of the semiconductor substrate. The adhesive resin finally becomes to be a sealing member, and a gap sandwiched by the semiconductor substrate and the glass substrate is formed above the light-receiving portion.
The semiconductor device is manufactured as stated below. At first, the semiconductor substrate on which the integrated circuit including the light-receiving portion is formed and the glass substrate is adhered via the adhesive resin. Next, the through holes are formed by etching the semiconductor substrate from the rear surface side thereof until electrodes at the front surface side expose, after the semiconductor substrate is made thin from the rear surface side to be a predetermined thickness. Further, the penetrating wiring layers are formed from inside the through holes toward the rear surface of the semiconductor substrate after insulating films are formed on internal surfaces of the through holes and the rear surface of the semiconductor substrate except bottom portions of the through holes being closed by the electrodes. After that, the rear surface of the semiconductor substrate is covered with a protective layer, and the external connection terminals are formed at the penetrating wiring layers. The glass substrate plays a role as a supporting substrate mechanically reinforcing the semiconductor substrate during these manufacturing processes.
However, there is a problem that scratches and cracks are easy to occur on the glass substrate because the front surface of the glass substrate is directly touched when the semiconductor device is carried or placed on a stage of a processing equipment, in the conventional semiconductor device manufactured by the method as stated above. The scratches and cracks occurred on the glass substrate scatter incident light, and become a factor deteriorating sensitivity of the light-receiving portion and manufacturing yield of the semiconductor device. The light incident from a diagonal direction is refracted by the adhesive resin, and incident on the light-receiving portion, and thereby, image pickup characteristics and so on at a peripheral edge portion of image deteriorates, when the adhesive resin has light-transmission property.